Macaws are small to large, often colourful New World parrots. Of the many different Psittacidae (true parrots) genera, six are classified as macaws: Ara, Anodorhynchus, Cyanopsitta, Primolius, Orthopsittaca, and Diopsittaca. Previously, the members of the genus Primolius were placed in Propyrrhura, but the former is correct as per ICZN rules. Macaws are native to Mexico, Central America, South America, and formerly the Caribbean. Most species are associated with forest, especially rainforest, but others prefer woodland or savanna-like habitats.

Large, dark (usually black) beaks, and relatively hairless, light colored, medial facial (facial patch) areas distinguish macaws. Sometimes the facial patch is smaller in some species, and limited to a yellow patch around the eyes and a second patch near the base of the beak in the members of the genus Anodorhynchus, or Hyacinth Macaw. It has been documented that a Macaw's facial feathers are unique as a human fingerprint.

Some of the macaw species are popularly known for their impressive size. The largest parrot in length and wingspan is the Hyacinth Macaw. The heaviest macaw is the Buffon's, although the heaviest parrot is the flightless Kakapo. While still relatively large parrots, the macaws of the genera Cyanopsitta, Orthopsittaca and Primolius are significantly smaller than the members of Anodorhynchus and Ara. The smallest member of the family, the Red-shouldered Macaw, is no larger than some parakeets of the genus Aratinga.

Macaws, like other parrots, as well as toucans and woodpeckers, are zygodactyl, having their first and fourth toe pointing backwards.

Extinctions and conservation status

The majority of macaws are now endangered in the wild. Six species are already extinct, and Spix's Macaw is now considered to be extinct in the wild. The Glaucous Macaw is also probably extinct, with only two reliable records of sightings in the 20th century. The greatest problems threatening the macaw population are the rapid rate of deforestation and the illegal trapping for the bird trade.

International trade of all Macaw species is regulated by the Convention on International Trade in Endangered Species of Wild Flora and Fauna (CITES). Some species of macaws for example, the Scarlet Macaw (Ara macao) are listed on Appendix I and may not be traded for commercial purposes. Other species for example, the Red-Shouldered macaw (Diopsittaca nobilis) are listed on Appendix II and may be legally traded commercially provided that certain controls are in place. The controls include a non-detriment finding, establishment of an export quota and issuing of export permits.

Hybrids

A common trend in recent years is hybridising macaws for the pet trade. Hybrids are typical macaws, with the only difference from true species being their genetics and their colors. Male offspring tend to take on the traits of the mother, and the females take the traits of the father. As for their temperament and behaviour, they seem to inherit traits of both parents.

Aviculturists have reported an over abundance of female blue and gold macaws in captivity, which differs from the general rule with captive macaws and other parrots, where the males are more abundant. This would explain why the blue and gold is the most commonly hybridised macaw, and why the hybridising trend took hold among macaws. Common macaw hybrids include Harlequins (Ara ararauna x chloroptera) and Catalinas (known as Rainbows in Australia, A. ararauna x macao)

Clay Licks

Macaws are fruit eaters but change their diet from time to time, due to lack of essential nutrients contained in each fruit. It is often hard for macaws to find ripe fruit, seasons may vary where certain fruits may not be available in the vicinity of their habitat. They are then forced fly far for ripe fruit or accept nearby fruit which may be unripe. In eating unripe fruit, Macaws suffer similar as a person would after eating unripe fruit. They get stomach aches. Like parrots, macaws have a unique way with dealing with this problem, by eating clay, which is believed to work as an antidote to the poisonous seeds they eat. The chemicals in the clay mix with the poison allowing it to pass through the bird's digestive system without harming the bird.

Dr. Donald Brightsmith, the principal investigator of the Tambopata Macaw Project, has been leading research at the Tambopata Research Center since 1999. Findings from the center located in the Amazon basin in southeastern Peru show that the soil macaws choose to consume at the clay licks they frequent did not have higher levels of cation exchange capacity (ability to adsorb toxins) than that of unused licks. What the findings do show is that the macaws, along with other bird species, prefer soil with higher levels of sodium.

It is possible that the birds are using taste to find soil that also meets other physiological needs. However, it is interesting to note that the macaws on the coast of Costa Rica do not use clay licks and this is possibly related to the fact that the mangroves which supply a portion of their diet are high in sodium.

Continuing projects at TRC are also showing a correlation between clay lick use and breeding season. Calcium for egg development - another hypothesis - does not appear to be a reason for geophagy during this period as peak usage is after the hatching of eggs. Contents of nestling crop samples show a high percentage of clay fed to them by their parents.